By Denise Upton

There’s a threat looming out there. A threat to our wildlife we are supposed to be living in harmony with. Many of us are unaware of this threat.

Here’s the scenario: We’re sitting in our living room and “something” catches our eye running across the floor. Did we really just see something? Then we open the pantry and find droppings. It’s confirmed. Mice have moved into your house and you have to get rid of them. Quickly!

We run to the hardware store and we have a choice of old-fashioned snap traps where we have to remove the dead mouse carcass or how about those nifty bait stations where the mice go in get some poisoned bait and we never see them again. Sounds like a no brainier, right?

Well, let me get you up to speed on what really happens when the mice “take the bait” so to speak.

First of all, let me give you a little lesson in rodenticide 101. The most popular brand of poison bait is D-Con. The key ingredients are brodifacoum, bromadiolone, difethialone or difenacoum. These are all what they call “second generation” rodenticides and are anti-coagulants that result in death from internal bleeding.

In June 2012, the EPA announced they are starting the process to ban second-generation rodenticides from the consumer market. In March 2013 the EPA started regulatory action to remove 12 D-con products from shelves of some retailers as the company Beckitt Benckisen (the manufacturer of D-Con) has refused to voluntarily remove these products. Even if these actions are imposed, you will still be able to purchase these products at some farm and ranch supply stores.

Why all the fuss over a few mice and some poison bait stations? Mice are not where the story ends. It’s just the beginning. Thousands of dogs and cats are exposed to this bait and injured or killed every year even though the bait stations are “supposedly” sealed. From 1993-2005 12,000 to 15,000 children under the age of 6 were reported to have exposure to rodenticides as reported by Poison Control.

As wildlife rehabilitators, what we see is exposure to our wildlife.

Secondary exposure occurs when wildlife consumes dead or dying rodents that have eaten poison bait. Since it is a slow acting poison it is often eaten over several days by rats and mice causing the deadly substance to accumulate in the animals’ systems reaching many times the lethal dose in their tissue. Predatory or scavenging wildlife that feed on them fall victim to secondary poisoning. Some of the animals affected are grey fox, coyote, kit fox (federally endangered), raccoon, fisher marten, bobcat, mountain lion, black bear, golden eagle, great horned owls, barn owl, all the hawk species and virtually anything that consumes rodents.

In essence we are killing our natural pest control species.

Ninety-two percent of all raptors in San Diego County tested positive, 79 percent of endangered San Joaquin kit foxes showed signs of anti-coagulant in their blood, and of 104 mountain lions tested since 2005 82 had the deadly poison in their system.

Since many of these animals typically retreat to their dens, burrows or other hiding places in the final stages of anti-coagulant poisoning, the numbers of non-target wildlife being killed by these compounds may be much higher.

Here in Tahoe we have many vacation homes that are only used during the summer. It’s common for these homeowners to purchase multiple boxes of D-Con and toss them under their homes to control the “mouse problem” while they are away during the winter. “Out of sight, out of mind” so to speak. While they are away the rodents consuming this bait, which can include our local squirrels and chipmunks which are also rodents, may leave the area under the house and become easy targets for our hungry wildlife.

I remember the call we received about a pine marten in someone’s garage. When we live trapped the sick animal we could tell he was in very bad shape and died soon thereafter. Within the next few days we got calls of two more pine martens in the same garage. We were able to save and release one of them. This garage was full of all sorts of stuff, but somewhere amid all of it was D-Con, which poisoned the mice and in turn killed the pine martens that consumed them.

Not many people have even seen these beautiful animals here in Tahoe and to see them die a slow agonizing death was heartbreaking.

We’ve received a record number of raptors at LTWC last year – eagles, hawks and owls. Some had obvious injuries and some were just found sitting on the ground for no apparent reason. Without expensive blood tests we can never be sure, but we suspect some sort of poison. Some of these animals -after they died from “something” are sent to fish and wildlife labs for further testing, as this has become a widespread issue throughout the state and the entire country.

We live in Tahoe among a multitude of wildlife. We battle voles in our lawn, squirrels in our attics and bears under our porches. There exists a delicate balance among our wildlife. By poisoning our mice we are in turn killing the very species such as hawks, coyotes and owls – to name a few – that control our rodents naturally.

Here’s a perfect example: Last summer my neighbor had a huge lawn and lots of voles to go with it. He also had a resident hawk that spent the day sitting atop a tree watching for his chance to help control these lawn pests. Day after day this same hawk swooped down and took off with a vole in his talons. Amazingly, last spring, as the snow melted, he didn’t seem to have the same vole problem. Nature had done what it does best – controlled the problem naturally compliments of our neighborhood hawk.

I know people see coyotes and immediately think of them as pet eating carnivores when they are actually omnivores. Did you know that up to 80 percent of their diet could consist of rodents dependent on where they live? Did you know that bears are actually attracted to the smell of D-con under your house?

I won’t even begin to talk about the illegal marijuana growers in our national forests killing multitudes of our wildlife by putting out deadly poisons in tin cans known as “wildlife bomb” surrounding their camps killing everything and their offspring that is unfortunate enough to come in contact with it. This is all to protect their crops and camps. This is why wildlife is being found miles away from any civilization dead and dying from these toxic poisons. If you want to read more on this, here’s a link.

We can do our small part to protect our wildlife. Please educate yourself before you reach for that box of rodent bait with any of the ingredients listed above. There are alternatives such as snap traps, catch and release traps (please no glue traps). Find the entrances the rodents are using and seal them or as a last resort bait stations with ingredients that do not cause secondary poisoning to our local wildlife. We have an obligation to keep the delicate balance of nature in line and to think twice about what or who is affected when we take the easy way to control that little mouse you just saw run across your floor. You could be killing more then the little mouse.

Denise Upton is president of the Lake Tahoe Wildlife Care board.